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How to be green with your greens

August 16, 2008|By BOB KESSLER

If you need to use a fungicide on plants in your yard, you may want to use an organic fungicide.

They are environmentally friendly and they can do a good job of controlling the disease problem. Some of the choices of an organic fungicide include sulfur, copper, oils and bicarbonates.

Sulfur is one of the oldest materials used to control diseases. It dates back more than 2,000 years. Sulfur is effective in preventing rusts, rose black spot, powdery mildews and other fungal diseases. It works by preventing fungal spore germination, so it must be in place before the disease problem develops.

Be sure to read the label if you plan to use sulfur because some plants can be injured by sulfur. Also, it has to be used when the temperature is lower than 80 degrees, so it is not one you can use in the summer months.

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Lime sulfur is a mixture of sulfur and lime and is mostly used as a dormant application on plants to prevent disease from developing. It should not be sprayed on foliage because it will burn the green tissue.

There are several combinations of copper that can be used on plants to kill bacteria and fungi. One you might recognize is bluestone or copper sulfate.

Another one you might recognize is called Bordeaux, which is a combination of copper sulfate and lime. Bordeaux mixture can be used to control fungi like powderymildew, downey mildew and anthracnose It will also control bacteria on plants such as bacterial leaf spot. When using a Bordeaux mixture, be sure to carefully read the directions, especially on fruit as you can injure the young tissue if you use too strong a mixture.

Our next class of materials is horticultural oils, which are formulations of mineral oil and Neem oil.

Horticultural oil is referred to as either dormant oil or summer oil. Dormant oils are meant to be applied to the plant when it is dormant and it is effective in controlling scale and other overwintering insects.

Summer oils are lighter oil and can be applied to green tissue during the summer months again to control various insects. Neem oil, which is relatively new in American landscaping, is made from the fruit and seed of the Neem tree. It is good as an insecticide or a fungicide.

Baking soda, which is sodium bicarbonate, has been used as a fungicide for many years. More recently the green industry has switched to using potassium bicarbonate and ammonium bicarbonate because the baking soda is ineffective against most diseases.

If you want to go more organic in your yard, there are some products you can use. Be sure to read the label on any product you plan to use to see what restrictions there are. Organic does not mean it is safe to use on any plant at any time.

- Much of the background material for this article came from a Purdue Extension factsheet, "Using Organic Fungicides," written by Jane Beckeman.

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